I once thought I would be working on detectors for terrorist explosives- I researched the terrorist explosives of choice, one of which is TATP - unusual in that is not a nitrate based explosive (this makes it harder to detect), it is the explosive that the shoe bomber tried to use. I made TATP as a kid for fun... it took a trip to ace hardware and a hair salon, so the ingredients are not hard to find. TATP makes gunpowder's burn speed look like an oily rag...

The making of a belt bomb would be simple in our free society, so- as you point out- why hasnt it happened? I dont know the answer, I think part of it is the fact that if a bus is blown up it will just make the news... If you hear about a bus blown up in New York by terrorists, will it stop you riding a bus? The answer is likely no...

In a large country it takes a HUGE event to terrorize the population... hell even the 9-11 horror really did not change the fact that 99.9999% of those that work in high rises go to work the next day....

I dont want to sound flip, but terrorism on the order that Isreal suffers would be just a severe annoyance for the US- the big groups want to destroy us, a simple bus bombing wouldnt do a thing to destroy us... It would be a tragedy, but life would go on.

I hope we keep in mind that it really does take a hell of a lot to really threaten our culture.... our reaction to terrorism may limit our freedom far more than the terrorist acts.